Conduction cells

[ThiaminePyroPhosphate]

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Hey,

I have a question regarding what is responsible for the upstroke potential of cardiac conduction cells (excluding SA node)?

I know that for the SA node, influx of Na+ leak channels allows it to reach threshold, which results in slow voltage gated Ca2+ channels to be open, and depolarized. What about the other cardiac conduction cells such as AV node, purkinje fiber, etc? I'm guessing that intercalated discs allow Na+ ions to diffuse across, and allow the threshold to be reached. Once the threshold is reached, is it the fast Na+ voltage gated channel or slow Ca2+ voltage that open in the conduction cells?

Also how does the conduction cells initiate the depolarization of cardiac myocytes of the atrium and ventricles? Is it through intercalated discs also?


Thanks!

 

[type12]

The electrical synapses allow for a synchronous contraction of the muscle. The nodes are a pause of sorts, that has a slower arrangement of channels to pause the signal. Na always opens first in all cells, followed by calcium channels. All the cells do the same thing.